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1-Piece Instrumentation, 40G and 40 Series

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Swagelok® 40G Series Ball Valve Technical Bulletin

40G Series Ball Valve Technical Bulletin

The Swagelok® 40 series one-piece instrumentation ball valve has performed reliably for nearly 40 years in multiple industries. Swagelok has modified the valve construction and developed an innovative assembly process. The result is the new 40G series ball valve, which features an expanded operating temperature rating, improved thermal cycling capabilities, and reduced potential for leaks.

Using a patent-pending seal design, the 40G series ball valve resists packing deformation, or “cold-flow,” for increased thermal performance and improved leak resistance. Its expanded temperature range, from –65 to 300°F (–53 to 148°C), meets application demands for both environmental and heated-process applications (Figure 1).

Figure 1.

The 40G Series ball valve’s expanded temperature range meets application demands for environmental and heated-process applications.

40G Series Heat Diagram Ball Valves


– applications in which the valve experiences thermal cycling due to fluctuating outside temperatures, such as:
  • Outdoor process instrumentation systems
  • Grab sample systems
  • Sample conditioning systems


– applications in which heat is applied to the process stream, such as:

  • Sample conditioning systems in heated enclosures
  • Laboratory applications:
  • Micro-reactors
  • Test hoods
  • Pilot plants
  • Research and development facilities

The 40G series valve is capable of operating with minimal service adjustments and maintenance required. Several aspects of the 40G series valve’s single-piece seal design contribute to its enhanced thermal performance and low-maintenance characteristics (Figure 2):

1. Hex-style packing bolt
2. Live-loaded packing system
3. Packing gland
4. Encapsulated patent-pending single-piece packing design
5. Enlarged trunnions
6. Trunnion pocket

40G Series Cross Section Ball Valve

Figure 2.

Cross-section of the 40G series ball valve

  • An encapsulated patent-pending single-piece packing design
  • Enlarged trunnions;
  • A live-loaded packing system;
  • New TFM® packing material; and
  • A trunnion pocket.

In addition, a new patent-pending assembly method ensures valve-to-valve consistency and reduces the need for packing adjustments in the field.

The 40G series valve is designed to provide a cycle life equal to or better than the 40 series valve in existing applications. It has equivalent dimensions to the 40 series, making 40G series valves dimensionally interchangeable with 40 series valves.

The new 40G series ball valve is available as a two-way valve for shut-off service in both a straight and angle pattern, as well as a three-way valve for switching service. The valves can be used in applications with working pressures up to 3,000 psig (206 bar).

The 40G series will replace several part numbers in the standard and live-loaded 40 series product lines, including the stainless steel 41, 42, and 43 models with 1/16 to 3/8 in. and 3 to 8 mm end connections. The existing 44 and 45 models will not change at this time.

40G Series Ball Valve Exploded

Figure 3

Encapsulated Patent-Pending Single-Piece Packing

The packing creates a functional seal inside the valve cavity and is designed to handle temperature fluctuations while limiting the potential for leaks. The 40G series ball valve utilizes an encapsulated single-piece packing to house the ball and trunnion portion of the valve ball stem for an uninterrupted, highly leak-resistant seal.

The 40G series stem is assembled into the single-piece encapsulated packing. This subassembly is then pressed into the valve cavity. The encapsulated packing completely surrounds the ball stem, minimizing damage during actuation and thermal cycling. (Figure 3)

Enlarged Trunnions

Packing material tends to deform with temperature changes, softening as temperatures rise and stiffening as temperatures fall. This expansion and contraction allows the packing material to flow or extrude into voids, or “dead spaces,” within the packing cavity or possibly even flow outside of the valve’s packing cavity.

Swagelok has decreased the amount of packing material in the 40G series valve’s packing cavity. To consume volume in the packing cavity with material other than the TFM packing, Swagelok added an additional trunnion to the 40G series valve’s 316 stainless steel ball stem. In addition, Swagelok enlarged the diameter of the trunnions to displace more packing volume.

Live-Loaded Packing System

After top loading the packing and stem subassembly into the packing cavity, 40G series valve assemblers place a packing gland over the valve stem. This gland slides over the upper trunnion to rest directly on top of the packing material. With a close fit around the trunnion and within the valve cavity, the gland fully contains the packing.

A series of disc springs rests on top of the packing gland and is secured by a packing bolt. The springs create a “live load” that is transferred to the gland and, subsequently, to the packing. The “live load” serves to maintain consistent sealing pressure on the packing through temperature fluctuations and compensate for wear.

TFM Packing Material

The 40G series valve features a modified PTFE packing material known as TFM®, an upgrade from the PTFE packing material in the 40 series valve. TFM has a higher resistance to cold-flow deformation during thermal cycling compared to standard PTFE.

Trunnion Pocket

Swagelok added a trunnion pocket in the bottom of the 40G series valve body. It serves as a deterrent to cold-flow and minimizes packing extrusion.

Innovative Assembly Method

In the patent-pending assembly process – known as the direct-load assembly method –assemblers add the series of disc springs over the ball stem. Then they compress the springs to a specific load using a special direct load method. The packing bolt is fastened to a specific point. The direct load tool is then removed, and the secured packing bolt maintains the valve load.

40G Series Valve Cutaway

Figure 4.

Internal view of the 40G series ball valve

Additional Design Improvements

The 40G series ball valve features additional design enhancements, including a hex-style packing bolt and modifications to the handle material and design.

The 40G series valve’s design and construction minimize the need for packing bolt adjustments in the field. However, the need for adjustments over time exists in some applications. The hex on the 40G series valve packing bolt (Figure 4) can be tightened by a standard deep-well socket wrench, which simplifies field adjustments.

All 40G series valve handle inserts are now made of powdered metal 300 series stainless steel. A double-flat stem handle is now standard on all 40G series valves.

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